Wing-shaped flow guide component for controlling hydraulic instability of pump turbine

Abstract

The invention belongs to the technical field of mechanical energy storage and hydroelectric generation, and discloses a wing-shaped flow guide component for controlling the hydraulic instability of a pump turbine. The pump turbine can stably work under the working condition of turbine power generation and the working condition of water pump water pumping through the wing-shaped flow guide component installed in the draft tube, and spiral vortex strips and pressure pulsation in the draft tube are relieved. The wing-shaped flow guide component in the middle of the straight cone section of the draft tube is connected with the wall face of the draft tube through an anchor chain. The spiral vortex strip enters the flow guide component, firstly, the vortex strip cannot move in the radial direction due to limitation of the wall face, the vortex strip is broken into a large number of small vortex structures after impacting the wall face, secondly, the device separates a dead water area from a main flow area, the vortex strip cannot obtain speed compensation of the main flow area, and therefore the circumferential speed is reduced, and the eccentric distance is reduced. The method can relieve the hydraulic instability of the pump turbine in the power generation working condition and the water pumping working condition at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of fluid machinery and hydraulic power generation, and in particular relates to an airfoil guide component for controlling hydraulic instability of a water pump turbine. Background Art

[0002] As the core component of a pumped-storage power station, the stable operation of the pump-turbine unit is directly related to the safety of the power station. The design of the pump-turbine unit must not only meet the pumping conditions, but also take into account the power generation conditions. Therefore, it is extremely difficult to ensure that the unit is in the optimal performance range under both pump and turbine conditions. As the peak and frequency regulation tasks of the pump-turbine become heavier and the regulation cycle becomes shorter, the instability problem caused by the spiral vortex belt in the tailwater pipe of the pump-turbine seriously affects the normal operation of the unit.

[0003] When the pump turbine is running in the turbine condition, the water flow direction is the same as the rotation direction of the runner. However, when running in the small opening condition, the water flow no longer flows according to the optimal condition, and is rapidly deflected downward by the runner and centrifugal force. This causes the water flow at the inlet of the tailwater pipe to have a large circumferential velocity, causing the central pressure inside the tailwater pipe to be low and the surrounding pressure to be high, forming a dead water area in the center. Finally, a large-scale eccentric spiral vortex is formed in the straight cone section or even the elbow section of the tailwater pipe.

[0004] When the pump turbine is operating in the pump mode, the tailwater pipe acts as the water inlet, and the internal flow pattern will affect the flow downstream. Under low flow conditions, the water flow in the tailwater pipe still spirals downstream, and then backflow occurs. At the same time, the low-frequency, high-amplitude pressure pulsation and unsteady excitation force will generate noise, and in severe cases, even cause fatigue fracture of the blades.

[0005] The low-frequency pressure pulsation caused by the vortex belt in the tailwater tube is an important factor affecting the operating stability of the turbine unit, which is not conducive to the long-term safe and stable operation of the unit. The airfoil guide component used in this method can prevent the spiral vortex belt from spiraling, use the wall surface to break up the large-scale vortex belt, reduce the circumferential speed and eccentricity of the vortex belt, and thus ensure the stability of the unit operation. Summary of the invention

[0006] In order to overcome the shortcomings of the prior art, the present invention proposes an airfoil guide component for controlling the hydraulic instability of a pump-turbine. Regardless of whether the pump-turbine is operating in a pump condition or a turbine condition, the airfoil guide device can improve the pressure distribution in the tailwater pipe, thereby achieving the purpose of suppressing large-scale spiral vortex bands in the tailwater pipe and the low-frequency and high-amplitude pressure pulsation induced by the spiral vortex bands.

[0007] To achieve the above-mentioned purpose, an airfoil guide component for controlling the hydraulic instability of a pump-turbine is disclosed, characterized in that: an airfoil guide component for controlling the hydraulic instability of a pump-turbine in bidirectional operation comprises an airfoil guide component (2), a conventional pump-turbine tailwater pipe (1) and an anchor chain (3); the tailwater pipe (1) comprises a straight cone section (11), an elbow section (12) and a diffuser section (13); the airfoil guide component (2) is a symmetrical rotating body airfoil flow component, designed with an airfoil (21) of an asymmetric airfoil structure, installed in the middle of the tailwater pipe straight cone section (11), and the central axis is colinear with the central axis of the tailwater pipe straight cone section (11); the airfoil guide component (2) is used to change the tailwater pipe flow field distribution characteristics of the pump-turbine in the power generation condition and the pumping condition, thereby suppressing the large-scale spiral vortex band in the tailwater pipe and the low-frequency and high-amplitude pressure pulsation induced by the spiral vortex band.

[0008] Furthermore, the airfoil guide component (2) is shaped in such a way that the upper and lower openings are larger and the middle opening is smaller, the upper end surface is parallel to the lower end surface, the diameter D3 of the lower end opening is larger than the diameter D1 of the upper end opening, and the diameter D2 of the middle portion is the smallest.

[0009] Furthermore, the height H2 of the airfoil guide component (2) is (0.11-0.15)H, the inlet diameter D1 is (0.1-0.12)D, wherein D is the inlet diameter of the tailwater pipe (1), the distance H1 between the inlet of the airfoil guide component (2) and the inlet of the tailwater pipe (1) is (0.02-0.05)H, wherein H is the height of the tailwater pipe straight cone section (11); the angle α between the chord length of the airfoil (21) and the center axis of the tailwater pipe straight cone section (11) is 2.5°-4°, and the maximum thickness t1 of the airfoil (21) is 15 cm-20 cm.

[0010] Furthermore, the airfoil guide component (2) is fixed to the inner wall surface of the tailwater pipe straight cone section (11) by means of a plurality of anchor chains (3), wherein the plurality of anchor chains (3) are respectively welded and fixed to the cross sections at 0.2H1 and 0.8H1 of the airfoil guide component (2), and the plurality of anchor chains (3) on each cross section are symmetrically distributed in the circumferential direction, and the arrangement of fixing the anchor chains (3) at the cross sections is exactly the same.

[0011] Furthermore, the anchor chain (3) has a certain flexibility, and when the water pump turbine is switching its working state, it can not only withstand a large water flow impact resistance, but also perform a small adaptive correction and adjustment on the working state of the airfoil guide component (2).

[0012] The advantages of the present invention after adopting the above technical solution are:

[0013] (1) Because the cross-sectional shape of the airfoil guide component is an airfoil, it can not only reduce the resistance of the guide device, but also play a two-way guide role in both turbine working conditions and water pump working conditions, reducing the vibration problem caused by frequent changes in working conditions, and helping to improve the overall stability of the unit;

[0014] (2) The pressure pulsation amplitude in the tailwater pipe can be reduced by 1 / 3 to 1 / 2, the frequency is reduced, and the eccentric distance of the vortex belt is effectively reduced, which has a significant effect on the pressure pulsation control;

[0015] (3) The airfoil guide component separates the dead water area from the mainstream area. The dead water area cannot obtain velocity compensation from the mainstream area, which in turn reduces the circumferential velocity and the eccentricity of the vortex belt, resulting in the vortex belt being unable to develop and move toward the periphery.

[0016] (4) When the vortex belt enters the airfoil guide component, its pressure gradually decreases and the axial velocity increases. The increase in axial velocity slows down the formation of the dead water zone, thereby improving the pressure distribution and effectively alleviating the pressure pulsation in the center of the draft tube;

[0017] (5) Since the vortex belt entering the airfoil guide device has limited internal space and is large at the top and bottom and small in the middle, it will hit the wall of the device, causing the vortex belt to break and eliminate some large-scale vortex belts, thereby fundamentally alleviating pressure pulsation;

[0018] (6) The present invention will not affect the normal working efficiency of the water pump turbine. The airfoil guide device has a simple structure, does not require an additional energy supply device and a complex control system, does not involve the replacement of other components of the hydropower station, and solves the problem of unit vibration induced by the spiral vortex of the water pump turbine under eccentric load conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments;

[0020] Figure 1 It is a schematic diagram of the structure of the overall device of the present invention;

[0021] Figure 2 It is a top view (top view direction) of the overall device of the present invention;

[0022] Figure 3 Sectional view of airfoil guide component (front view direction);

[0023] Figure 4 FIG. 1 is a diagram showing a fixing method of an airfoil guide component of the present invention;

[0024] Figure 5 This is a working principle diagram of the airfoil guide component of the present invention;

[0025] Wherein: 1- tailwater pipe, including: 11- straight cone section, 12- elbow section, 13- diffuser section, 2- airfoil guide component, 21- airfoil, 3- anchor chain. DETAILED DESCRIPTION

[0026] like Figure 1-4 As shown, an airfoil guide component for controlling hydraulic instability of a pump turbine,

[0027] The invention is characterized in that: the airfoil guide component for controlling the hydraulic instability of bidirectional operation of a pump-turbine comprises an airfoil guide component 2, a conventional pump-turbine tailwater pipe 1 and an anchor chain 3; the tailwater pipe 1 comprises a straight cone section 11, an elbow section 12 and a diffuser section 13; the airfoil guide component 2 is a symmetrical rotating body airfoil flow component, designed by an airfoil 21 of an asymmetric airfoil structure, installed in the middle of the tailwater pipe straight cone section 11, and the central axis is colinear with the central axis of the tailwater pipe straight cone section 11; the airfoil guide component 2 is used to change the tailwater pipe flow field distribution characteristics of the power generation condition and the pumping condition of the pump-turbine, thereby suppressing the large-scale spiral vortex bands in the tailwater pipe and the low-frequency and high-amplitude pressure pulsations induced by them.

[0028] like Figure 4 As shown, in one embodiment, the airfoil guide component 2 is obtained by rotating the airfoil 21 360° around the central axis of the draft tube straight cone section 11, presenting a bilaterally symmetrical structure, and the airfoil 21 is an asymmetric airfoil with good hydrodynamic performance. The airfoil guide component 2 is in a shape with large upper and lower openings and a small middle opening, the upper end face is parallel to the lower end face, the diameter D3 of the lower end opening is larger than the diameter D1 of the upper end opening, and the diameter D2 of the middle part is the smallest.

[0029] like Figure 1 As shown, in one embodiment, the distance H1 between the airfoil guide component 2 and the inlet of the tailwater tube 1 is (0.02-0.05)H, where H is the height of the tailwater tube straight cone section 11, the height H2 of the airfoil guide component 2 is (0.11-0.15)H, the inlet diameter D1 is (0.1-0.12)D, where D is the inlet diameter of the tailwater tube 1, the angle α between the chord length of the airfoil 21 and the central axis of the tailwater tube straight cone section 11 is 2.5°-4°, and the maximum thickness t1 of the airfoil 21 is 15cm-20cm.

[0030] like Figure 1 , Figure 2 and Figure 4As shown, in one embodiment, the airfoil guide component 2 is welded to the inner wall surface of the straight cone section of the draft tube by 8 anchor chains 3, of which 4 anchor chains 3 are welded to the section at 0.2H1 of the airfoil guide component 2, and the other 4 anchor chains 3 are welded to the section at 0.8H1 of the airfoil guide component 2. The 4 anchor chains on each section are symmetrically distributed in the circumferential direction, the angle between every two anchor chains is 90°, and the arrangement of the anchor chains in the upper and lower sections is exactly the same.

[0031] like Figure 4 As shown, in one embodiment, the anchor chain (3) has a certain flexibility, and when the pump turbine is switching its working state, it can not only withstand a large water flow impact resistance, but also perform a small adaptive correction and adjustment on the working state of the airfoil guide component (2).

[0032] like Figure 5 As shown, in one embodiment, when the airfoil guide device operates in a turbine condition, the water flows from the tailwater pipe inlet to the tailwater pipe outlet, and a large number of spiral vortex belts will enter the guide device from the upper opening of the airfoil guide device. First, due to the limitation of the wall, the vortex belt cannot move radially, and after hitting the wall, it breaks into a large number of small vortex structures. Secondly, the wall separates the dead water area from the mainstream area, and the vortex belt cannot obtain the speed compensation of the mainstream area, resulting in a decrease in the circumferential speed and a decrease in the eccentricity. When the airfoil guide device operates in a water pump condition, the water flows from the tailwater pipe outlet to the tailwater pipe inlet. Under the combined effect of the backflow phenomenon and the rotation of the runner, the water flow in the tailwater pipe still spirals downstream. The airfoil guide device can still break the vortex belt while reducing the circumferential speed and eccentricity of the vortex belt, thereby reducing the pressure pulsation and unit vibration problems from the root.

[0033] Under the above-mentioned implementation mode, the invention purpose of an airfoil guide component for controlling the hydraulic instability of a pump-turbine can be achieved, and those skilled in the art can select it according to actual conditions. The airfoil guide component for controlling the hydraulic instability of a pump-turbine provided by the present invention can be applied to the hydraulic stability control of a pump-turbine to enhance the reliability of the bidirectional operation of the pump-turbine.

[0034] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. An airfoil guide component for controlling hydraulic instability of a pump-turbine, characterized in that: The airfoil guide component for controlling the hydraulic instability of a pump-turbine in bidirectional operation comprises an airfoil guide component (2), a conventional pump-turbine tailwater pipe (1) and an anchor chain (3); the tailwater pipe (1) comprises a straight cone section (11), an elbow section (12) and a diffuser section (13); the airfoil guide component (2) is a symmetrical rotating body airfoil flow component, designed with an airfoil (21) of an asymmetric airfoil structure, installed in the middle of the tailwater pipe straight cone section (11), and the central axis is colinear with the central axis of the tailwater pipe straight cone section (11); the airfoil guide component (2) is used to change the tailwater pipe flow field distribution characteristics of the pump-turbine in the power generation condition and the pumping condition, thereby suppressing the large-scale spiral vortex band in the tailwater pipe and the low-frequency and high-amplitude pressure pulsation induced by the spiral vortex band.

2. The airfoil guide component for controlling hydraulic instability of a pump-turbine according to claim 1, characterized in that: The airfoil guide component (2) is shaped in such a way that the upper and lower openings are larger and the middle opening is smaller, the upper end surface is parallel to the lower end surface, the diameter D3 of the lower end opening is larger than the diameter D1 of the upper end opening, and the diameter D2 of the middle portion is the smallest.

3. The airfoil guide component for controlling hydraulic instability of a pump-turbine according to claim 1, characterized in that: The height H2 of the airfoil guide component (2) is (0.11-0.15)H, the inlet diameter D1 is (0.1-0.12)D, where D is the inlet diameter of the tailwater pipe (1), and the distance H1 between the inlet of the airfoil guide component (2) and the inlet of the tailwater pipe (1) is (0.02-0.05)H, where H is the height of the tailwater pipe straight cone section (11); the angle α between the chord length of the airfoil (21) and the center axis of the tailwater pipe straight cone section (11) is 2.5°-4°, and the maximum thickness t1 of the airfoil (21) is 15 cm-20 cm.

4. The airfoil guide component for controlling hydraulic instability of a pump-turbine according to claim 1, characterized in that: The airfoil guide component (2) is fixed to the inner wall surface of the tailwater pipe straight cone section (11) by means of a plurality of anchor chains (3), wherein the plurality of anchor chains (3) are respectively welded and fixed to the cross sections at 0.2H1 and 0.8H1 of the airfoil guide component (2), and the plurality of anchor chains (3) on each cross section are symmetrically distributed in the circumferential direction, and the fixed arrangement of the anchor chains (3) at the cross sections is completely the same.

5. The airfoil guide component for controlling hydraulic instability of a pump-turbine according to claim 1, characterized in that: The anchor chain (3) has a certain flexibility, and when the water pump turbine is switching its working state, it can not only withstand a large water flow impact resistance, but also perform a small adaptive correction and adjustment on the working state of the airfoil guide component (2).

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